The invention relates to an apparatus for projecting video images or pictures in color onto a large screen. There are several different types of such apparatus, which are generally called video projectors. The most commonly found involves an objective or lens projecting the image onto the large screen. The image or picture is supplied by three monochrome television tubes, each tube forming an image of one of the three primary colors. There are also video projectors with an optical modulator interposed between a light source and the screen.
The disadvantage of video projectors of the first type is that the image obtained on the large screen is not very bright and has limited resolution. Thus, the luminous flux reaching the screen is at most 150 lumens in the known video projectors. It is difficult to increase the flux without exceeding the limiting temperature for heating the phosphor strips of the tubes and the generally plastic lenses. It is certainly possible to increase the luminous flux by cooling the tubes, but a cooling installation is complicated and cumbersome.